Field of the Invention
The invention relates to an apparatus for impressing a corrugation into a metallic smooth pipe, said apparatus having a corrugating device which is driveable in rotation, through which the pipe is moved in its longitudinal direction and which produces the corrugation in the circumferential direction of the pipe by rotation, wherein the corrugating device has a corrugator head which is rotatable about its axis, and a hollow shaft on which the corrugator head is firmly fitted and via which the corrugator head is driveable in rotation, and also to a method for producing the corrugation.
Description of Related Art
An apparatus for manufacturing corrugated pipes is described for example in EP 1 084 774 B1. It is used for manufacturing metal pipes that are flexible on account of their corrugation. The corrugated metal pipes are for example used in the cable industry as electrical conductors of high-frequency cables or as a covering for electrical and optical cables, or they are used for transporting gases or liquids.
In the abovementioned known apparatus according to EP 1 084 774 B1, a pipe is formed from a longitudinally entering metal strip which is welded at a longitudinal slit. The obtained smooth pipe is then corrugated transversely to its longitudinal, direction in a corrugating device which the pipe runs through in its longitudinal direction. The corrugating device consists of a corrugator head in which a corrugator disk is rotatably mounted, said corrugator disk impressing the corrugation into the pipe upon operation of the corrugating device. The corrugator head is set into rotary movement by a hollow shaft on which the corrugator head is firmly fitted, by means of an electric motor. For the quality of the corrugation and a consistently efficient corrugating device, a uniformly and concentrically rotating corrugator head is crucial.
The rotation of the corrugator head, and thus of the corrugator disk, is influenced in particular by the quality of balancing of the corrugator head and by the state of the bearings of the hollow shaft. When the corrugator head is set up, the position of the corrugator disk that is mounted in a radially displaceable manner is selected such that the corrugation depth of the corrugated pipe to be produced corresponds to the desired value. The radial displacement of the corrugator disk together with its mount makes it necessary to balance the corrugator head with counterweights. A poorly balanced corrugator head can be recognized for example by the operator of the apparatus from more or less highly pronounced mechanical vibrations thereof. These vibrations can result in considerable damage to the hollow shaft bearings or to bearings of the corrugator head. Similarly, worn hollow shaft bearings contribute to a worsening in the rotary movement of the hollow shaft and thus of the corrugator head, and this can be manifested by a worsening in the quality of the flexible metal pipe.